How To Measure Your Dog's Collar. Do not measure right behind your dog’s armpits; Adjust the collar to match the measured distance.
When measuring the neck, wrap the tape measure just below the narrow part where she normally wears a collar. Do not measure right behind your dog’s armpits; Find your dog’s back length (or topline) by placing the start of your tape measure on the base of your dog's neck.
Alternatively you can refer to our average neck size list per dog breeds.
Do not measure end to end. Do not use your dog’s previous collar size as manufacturers use different methods to measure them. To measure your dog, use a cloth or flexible steel tape measure. Add two inches to the measurement for the best collar size.